The invention is directed to silver alloy wires for jewelry, especially for jewelry chains which consists of a solder containing nucleus and a jacket of silver or a silver alloy.
So-called silver-solder nucleus wires are preferably used for the production of jewelry chains. These silver-solder nucleus wires consist of fine silver or of silver alloys which contain a nucleus of a lower melting silver hard alloy. The silver fineness content of the wires for the most part is 835 or 925 per thousand. Chains are prepared from these wires on special machines, which then are treated with flux materials and talcum powder. Subsequently they are heated in continuous heating oven whereby in the link, i.e. the contact place of two wire ends of each chain member a small amount of solder must be melted in order that there is formed a solder joint of sufficient strength inside each chain member.
In place of solder nucleus wires there are also employed solid wires of silver alloys, likewise in a fineness content of 835 or 925 per thousand. The working of these wires to jewelry chains is substantially more expensive since a powdery solder must be applied in the narrow links in order that there can be formed a solder joint of sufficient strength between the wire ends of each chain member.
A greater portion of the jewelry chains are additionally shaped by rolls and are turningly worked with diamond tools (so called diamonding). It is important thereby that the silver fineness content of the chain not be changed in these additional operations.
With the previously known silver alloy nucleus wires it is a matter of wires which consist of a jacket of fine silver or silver weakly alloyed with copper or cadmium (maximally up to 5 weight %) and a nucleus of a low melting silver hard alloy with an average silver content of about 40 to 70%. The total fineness content of the solder nucleus wire of 835 to 925 is established by the variable silver portion of the alloy and the non-noble alloys of the fine silver jacket.
There are also known silver solder nucleus wires which consist of a wire shaped nucleus of copper which is surrounded by a thin tubular shaped silver hard alloy on which is located a substantially thicker silver jacket.
Since the silver hard alloys for the most part are brittle and therefore very difficult to mold there occurs in the production of such silver-alloy nucleus wires great difficulties. If the brittle alloy nucleus or the alloy layer splits in the preparation of the wire there are formed alloy nucleus wires with faulty places not ascertainable from the exterior which do not contain solder and therefore lead to large amounts of scrap in the preparation of the jewelry chains.
Besides if these known solder nucleus wires are worked by so-called diamondization, i.e. chipping away of the fine silver jacket then the original fineness content of the wire changes to lower values in the jewelry chains. Therewith the value fixed in applying the chasing can no longer be maintained in the finished chains.
A further disadvantage of the known solder nucleus wires with hard, brittle wire nuclei is to be seen in the shaping of round wires and profile wires, for example, rectangular or semicircular cross section. The hard nucleus of silver solder scarcely changes its round shape with the profile rolls, only the ductile silver presses off laterally. As a result there are formed profile wires with extremely thin wall strength in spots which lead to solder breakthroughs with the solder of the jewelry chains, i.e. solder leavenings, whereby the chain is unusable.
A further disadvantage of the previously known silver solder nucleus wires is that because of the relatively large portion of solder, which is caused by the establishment of the fineness content, the solder flux is very difficult to influence at solders of the chains.
Therefore it was the problem of the present invention to create silver alloy wires for jewelry, especially for jewelry chains consisting of a solder containing nucleus and a silver or silver alloy jacket, which do not have the above described disadvantages, particularly show no solder outbreaks in the working and also are capable of being chased in the diamondization. Besides they should be easily producible and processible.